Metered dose inhalers (MDIs) are medication delivery devices that are often used to deliver a pharmaceutical formulation including one or more pharmaceutically active compounds to a human or other mammalian patient.
Typically, the pharmaceutical formulation is delivered by the MDIs in unit doses in the form of an aerosol. Each actuation of the MDI delivers one unit dose. The unit dose is expelled by the MDI and is taken into the body of the patient upon inhalation, via the nose or mouth. The pharmaceutical formulation is then delivered to the lungs of the patient. Metered dose inhalers are typically used for the treatment of respiratory infections and disorders including respiratory tract infections, obstructive lung disease, inflammatory lung disease and chronic obstructive pulmonary disease. Asthma treatment is a particularly commonly use of MDIs.
Such an MDI is for example disclosed in WO 2011/071788 A1. The inhaler comprises a mechanical dose counter having an indicator member which undergoes predetermined count-indicating motion when a dose is dispensed from the inhaler.
An alternative arrangement is disclosed in WO 2016/030844 A1. This document describes a metered dose inhaler having trigger members which upon depression of a canister trigger electrical switches thereby counting doses being released from the canister.
In the field of MDIs, it is desired to provide the inhalers not only with a counting function in order to count the dispensed or remaining doses but also with additional functions such as monitoring functions or evaluation functions. Based on these additional functions the physician or patient may for example monitor the frequency of dispensed doses and the point of time when these doses have been dispensed. Experience shows that it is difficult to confirm the reliability of the dose counting function when providing inhalers with such additional monitoring functions.